Percarboxylic acids are utilized to oxidize cyclic ketones to lactones and omega-hydroxycarboxylic acids under Baeyer-Villiger conditions [Ber., 32, 3625 (1899); 33, 858 (1900)]. This procedure requires the preliminary preparation of the percarboxylic acid reagent; and the presence of the percarboxylic acid and the corresponding carboxylic acid byproduct results in the formation of undesirable derivatives of these carboxylic acid reactants.
As an alternative procedure, hydrogen peroxide has been substituted for percarboxylic acid. Hydrogen peroxide is unreactive unless it is in combination with a catalyst such as an oxyacid of Group IV-VI metal. A main disadvantage of the hydrogen peroxide route is the need for a large quantity of the catalyst component.
U.S. Pat. No. 3,064,008 describe a process for oxidizing cyclohexanone to epsilon-caprolactone with peracetic acid or acetaldehyde monoperacetate. Other prior art which describe conversion of cyclic ketones to lactones and/or omega-hydroxycarboxylic acids with an organic peracid or hydroperoxide include U.S. Pat. Nos. 3,517,033; 3,728,358; 3,833,613; and 3,483,222.
U.S. Pat. No. 4,013,691 describes a process for oxidizing cyclohexanone with molecular oxygen in the presence of an aldehyde, a soluble compound of a Group VIII type metal, and a ligand compound to produce epsilon-caprolactone.
Of more specific interest with respect to the present invention is prior art relating to oxidation of cyclic ketones to lactones and omega-hydroxycarboxylic acids with hydrogen peroxide and various catalyst systems. Pertinent United States patents include 3,428,656; 3,590,080; 4,171,313; 4,213,906; 4,286,068; and 4,353,832.
There is continuing interest in the development of new and improved processes for the production of lactones and omega-hydroxycarboxylic acids from cyclic ketone starting materials.
Accordingly, it is an object of this invention to provide a process for converting a cyclic ketone to lactone and omega-hydroxycarboxylic acid products by oxidation under Baeyer-Villiger conditions in the presence of a zeolite catalyst.
It is another object of this invention to provide a process for converting a cyclic ketone to a lactone product by shape-selective oxidation with hydrogen peroxide in the presence of a zeolite catalyst having a Constraint Index between about 0.4-10.
It is a further object of this invention to provide a process for converting a cyclic ketone to an omega-hydroxycarboxylic acid product by shape-selective oxidation with hydrogen peroxide in the presence of a zeolite catalyst having a Constraint Index between about 1-12.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.